This is a program-project which encompasses a broadly based confederation of interrelated cardiopulmonary research projects dealing with impaired blood and tissue oxygenation and the pathophysiological consequences thereof. Scientific emphasis is focused on pulmonary gas exchange and myocardial oxygen delivery, with the myocardial effort including a multifaceted assault on the difficult barriers to our understanding and treatment of coronary artery disease. Sub-programs include: "Coronary Circulation in Normal and Abnormal States" focusing on the evaluation of heterogeneous myocardial perfusion, including assessment of regional perfusion; "Kinetics of Gas Exchange in the Lung and Tissues" investigating the mechanism an kinetics of the Haldane effect, as well a studying the speed of the Bohr shift in the intact erythrocyte; "Factors Influencing Distribution of Ventilation", having as its primary goal the determination of the distribution of ventilation-perfusion ratios from steady-state measurements of intrapulmonary elimination of several inert gas tracers; and "Comparative Electrophysiological Behavior of Atrial Specialized Fibers and Purkinje Fiber; Electrogenic Basis for Positive Chronotropic Effects of Cardiac Glycosides".